Tube yoke for a driveshaft assembly

ABSTRACT

Tube yoke designs with each having a tube seat, lugs and stiffening ribs are disclosed. The tube seats each have a base, a wall and the stiffening ribs. The lugs project outwardly from the tube seat. The stiffening ribs are located within the tube seat to reduce the amount of radial deformation experienced by the tube seat when a torque force is applied.

RELATED APPLICATIONS

This application claims the benefit of and is a continuation of pendingapplication granted Ser. No. 14/564,487 filed Dec. 9, 2014 which ishereby incorporated by reference in its entirety. Application Ser. No.14/564,487 claimed the benefit of and is a continuation application fromapplication Ser. No. 13/261,596, which is now granted U.S. Pat. No.8,939,845. Application Ser. No. 13/261,596 is a national stageapplication of the International Application which was granted serialno. PCT/US2011/001499, filed Aug. 25, 2011, which claims the benefit ofthe Provisional Application which was granted Ser. No. 61/377,546, filedon Aug. 27, 2010. The International Application granted serial no.PCT/US2011/001499, the Provisional Application granted Ser. No.61/377,546, the continuation application Ser. No. 13/261,596 and U.S.Pat. No. 8,939,845 are hereby incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION

This invention relates in general to a driveshaft assembly. Inparticular, this invention relates to a driveshaft assembly having animproved tube yoke design which enhances performance of the driveshaftassembly when torque is applied thereto.

A driveline assembly is used to transmit rotational power from a source,such as an engine, to a driven component, such as a pair of wheels. In atypical driveline assembly, a driveshaft assembly is included. In mostcases, the driveshaft assembly includes a driveshaft tube and a tubeyoke. The tube yoke usually includes a tube seat, which is connected tothe driveshaft tube, and a pair of spaced apart lugs.

The tube yoke is subject to torque loads. The torque loads can causeradial deformation of the tube yoke and, specifically, the tube seat.Radial deformation, and especially non-uniform radial deformation, canbe problematic and can be caused when torque is applied to thedriveshaft assembly by rotating the assembly in a clockwise direction orwhen torque is applied to the driveshaft assembly by rotating theassembly in a counterclockwise direction.

Accordingly, it would be desirable to provide an improved tube yoke thatreduces the amount of radial deformation which occurs to a tube seatwhen torque is applied to the driveshaft assembly and enhances theperformance of the driveshaft assembly by improving the interaction ofthe tube yoke and the driveshaft tube.

BRIEF SUMMARY OF THE INVENTION

The invention is directed to embodiments of a tube yoke for a driveshaftassembly.

In an embodiment, a tube yoke for a driveshaft assembly has a tube seatwith a base, a wall, and two pairs of stiffening ribs. The two pairs ofribs are formed as one unitary body that connect at the base. Eachstiffening rib extends to the end surface of the wall and in each pairone of the stiffening ribs of the pair is oriented opposite the otherstiffening rib of the pair. The oppositely oriented stiffening ribs areunitarily connected along the inner surface of the base with a filletbut they do not extend across an opening of said wall surrounding eachstiffening rib.

In another embodiment, a tube yoke for a driveshaft assembly has a tubeseat with a base, a wall, and two pairs of stiffening ribs. Eachstiffening rib comprises an outer end portion which is attached to awall middle portion and a pair of side portions and a front surface.Each stiffening rib terminates before it reaches the end surface of thewall in a discrete rectangular top surface and each stiffening ribterminates before it reaches a base center portion. At least a portionof the pair of side portions and the front surface of each have arectangular shape. The stiffening ribs are unitarily connected along theinner surface of said base but do not extend across an opening of saidwall surrounding each stiffening rib.

In another embodiment, a tube yoke for a driveshaft assembly has a tubeseat with a base, a wall, and two pairs of stiffening ribs. Eachstiffening rib comprises a portion attached to the wall and a pair ofside portions. Each stiffening rib terminates before it reaches an endsurface of the wall in a discrete polygon top surface. Each stiffeningrib terminates in a discrete polygon front surface before it reaches thebase so that the ribs do not form a unitary body with one another. Atleast a portion of the pair of side portions have a discrete polygonshape. The stiffening ribs are unitarily connected along the innersurface of the base but do not extend across an opening of the wallsurrounding each stiffening rib.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of a tube yoke known in the art;

FIG. 2 is a perspective view of a tube yoke in accordance with anembodiment of the invention;

FIG. 3 is a perspective sectional view of the tube yoke of FIG. 2;

FIG. 4 is a front view of the tube yoke of FIG. 2;

FIG. 5 is a perspective view of a tube yoke in accordance with anembodiment of the invention;

FIG. 6 is a perspective sectional view of the tube yoke of FIG. 5;

FIG. 7 is a front view of the tube yoke of FIG. 5;

FIG. 8 is a perspective view of a tube yoke in accordance with anembodiment of the invention;

FIG. 9 is a perspective sectional view of the tube yoke of FIG. 8;

FIG. 10 is a front view of the tube yoke of FIG. 8;

FIG. 11 is a perspective view of a tube yoke in accordance with anembodiment of the invention;

FIG. 12 is a perspective sectional view of the tube yoke of FIG. 11;

FIG. 13 is a front view of the tube yoke of FIG. 11;

FIG. 14 is a perspective view of a tube yoke in accordance with anembodiment of the invention;

FIG. 15 is a perspective sectional view of the tube yoke of FIG. 14;

FIG. 16 is a front view of the tube yoke of FIG. 14;

FIG. 17 is a perspective view of a tube yoke in accordance with anembodiment of the invention;

FIG. 18 is a perspective sectional view of the tube yoke of FIG. 17;

FIG. 19 is a perspective view of a tube yoke in accordance with anembodiment of the invention; and

FIG. 20 is a perspective sectional view of the tube yoke of FIG. 19.

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the invention may assume various alternativeorientations and step sequences, except where expressly specified to thecontrary. It is also to be understood that the specific devices andprocesses illustrated in the attached drawings, and described in thefollowing specification are simply exemplary embodiments of theinventive concepts. Hence, specific dimensions, directions, or otherphysical characteristics relating to the embodiments disclosed are notto be considered as limiting, unless expressly stated otherwise. Also,although they may not be, like elements in various embodiments may becommonly referred to with like reference numerals within this section ofthe application.

Additionally, the invention will be described in connection with apassenger vehicle driveshaft assembly. However, it would be understoodby one of ordinary skill in the art that the tube yoke and method ofreducing the deformation of a tube yoke described herein haveapplications to commercial and off-highway vehicle driveshaftassemblies. Furthermore, it would be understood by one of ordinary skillin the art that the tube yoke of the present invention could haveindustrial, locomotive, and aerospace applications.

Referring now to the drawings, there is illustrated in FIG. 1 a tubeyoke 10 known in the art. The tube yoke 10 comprises a tube seat 12 anda pair of outwardly projecting lugs 14 attached to the tube seat 12.

The tube seat 12 comprises a wall 16 and a base 18. The wall 16 includesan inner surface 20, an end surface 21, and an outer surface 22. Thebase 18 has an inner surface 28 and an outer surface 30. The wall 16 isattached to the base 18 and is formed in a unitary fashion with the base18. The wall 16 and the base 18 are concentric about an axis 31.

The inner surface 20 of the wall 16 substantially defines an innercircumference 24 and the outer surface 22 of the wall 16 substantiallydefines an outer circumference 26. Typically, the outer circumference 26is attached to a driveshaft tube (not depicted) to form a driveshaftassembly. When the driveshaft assembly is formed, the base 18 isperpendicular with the driveshaft tube.

Along with the wall inner surface 20, the base inner surface 28 definesa cavity 34. The cavity 34 helps to reduce the weight of the tube yoke10. The outer surface 30 of the base 18 defines an outer circumference38 of the base 18. In an embodiment, the outer circumference 38 of thebase 18 is greater than the outer circumference 26 of the wall 16. Inthis embodiment, the difference between the circumferences 26, 38 maydecrease gradually from the base 18 to the wall 16.

The inner circumference 24 and outer circumference 26 of the wall 16 maybe substantially uniform. As such, the wall 16 may have a uniformthickness. However, the inner circumference 24 of the wall 16 maygradually increase from where the wall 16 is attached to the base 18 tothe end surface 21 of the wall 16. Additionally, the outer circumference26 of the wall 16 may gradually decrease from where the wall 16 isattached to the base 18 to the end surface 21 of the wall 16. Thus, thewall 16 may gradually decrease in thickness from one end portion 37 ofthe tube seat 12 to the other 39.

In an embodiment, the base 18 has a center portion 32 and edges portions35. The center portion 32 and edges portions 35 extend from the innersurface 28 to the outer surface 30 of the base 18. The edge portions 35and are attached to the wall 16 on one end and the center portion 32 onanother. The edge portions 35 separate portions of the center portion 32from the wall 16. The center portion 32 is oriented in a generallyperpendicular relationship to the axis 31 and has a generally roundedsemi-cylindrical shape which extends from one edge of the inner surface20 of the wall 16 to an opposite edge. The center portion 32 may have araised portion 33 in its center. The raised portion 33 gradually reducesin thickness towards the wall 16.

The lugs 14 are formed in a unitary fashion with the tube seat 12. Thelugs 14 are attached to the outer surface 30 of the base 18 and projectoutwardly therefrom. The lugs 14 are spaced apart from each other byapproximately 180 degrees. Each lug 14 has a crosshole 36 which isformed through it. The crossholes 36 are aligned. In transmittingrotational power, the lugs 14 connect the driveshaft assembly to anotherportion of the driveline assembly (not depicted).

FIGS. 2-16 show additional embodiments of a tube yoke 40.

The tube yoke 40 comprises a tube seat 42 and a pair of lugs 44. Eachlug 44 is formed in a unitary manner with the tube seat 42 and projectsoutwardly therefrom. When forming the driveshaft assembly, the tube seat42 is attached to the driveshaft tube adjacent an end 45 of the tubeseat 42. Preferably, the tube seat 42 is concentric with the driveshafttube.

The tube seat 42 comprises a wall 46 and a base 48. The wall 46 isformed in a unitary manner with the base 48. In an embodiment, the tubeseat 42 has an outer surface, defined by outer surfaces 52, 62 of thewall 46 and the base 48 that has a generally cylindrical shape. In thisembodiment, the wall 46 and the base 48 are concentric about a centralaxis 41.

The central axis 41 extends through the base 48. The base 48 has aninner surface 60 and outer surface 62. In certain embodiments like theones shown in FIGS. 8-16, the base gradually decreases in thicknesstoward the central axis 41. When the tube yoke 40 is attached to adriveshaft tube, the inner surface 60 of the base 48 is positionedsubstantially perpendicularly to the driveshaft tube. The outer surface62 defines an outer circumference 43 of the base 48.

Additionally, the base 48 has a center portion 64 which extends from itsinner surface 60 to its outer surface 62. In an embodiment, the centerportion 64 is located equidistant from the wall 46. In certainembodiments like the ones shown in FIGS. 8-16, the base 48 comprises anedge portion 65. The edge portion 65 surrounds the center portion 64 andseparates the center portion 64 from the wall 46. Also, in theembodiments illustrated in FIGS. 8-16, the inner surface 60 of the base48 adjacent the center portion 64 has a generally conical shape. Inthese embodiments, the conical shape may include a generallysemispherical shaped portion. Also, in these embodiments, the base 48gradually decreases in thickness from the wall 46 to the center portion64 toward the central axis 41.

The wall 46 is defined by an inner surface 50, an end surface 51, andouter surface 52. The inner surface 50 substantially defines an innercircumference 53 of the wall 46. In an embodiment best shown in FIG. 6,the inner surface 50 of the wall 46 may comprise a fillet 88 adjacentwhere the wall inner surface 50 and base inner surface 60 are attached.Also, the outer surface 52 of the wall 46 substantially defines an outercircumference 54 of the wall 46. In an embodiment, the outercircumference 43 of the base 48 is larger than the outer circumference54 of the wall 46.

The wall 46 has a height 55 which can be measured as the distance fromthe inner surface 60 of the base 48 to the end surface 51 of the wall46. The position of the inner surface 60 of the base 48 may vary betweenembodiments of the present invention. Accordingly, the height 55 of thewall 46 may vary between embodiments of the present invention as can thethickness of the base 48.

To form the driveshaft assembly, the wall 46 is attached to thedriveshaft tube. Thus, after forming the driveshaft assembly, the outersurface 52 of the wall 46 abuts the driveshaft tube. In certainembodiments, the wall 46 is annular. Additionally, it may be preferablethat the end surface 51 has a uniform thickness for facilitating theattachment of the tube yoke 40 to the driveshaft tube. Therefore, incertain embodiments, the inner circumference 53 and outer circumference54 of the wall 46 are substantially uniform along the axis 41.

As discussed, the base outer surface 62 and the wall outer surface 52define the outer surface of the tube seat 42. As illustrated, the lugs44 project outwardly from the outer surface of the tube seat 42. Morespecifically, the lugs 44 are attached to the outer surface 62 of thebase 48 and project outwardly therefrom.

The lugs 44 are spaced apart from each other by approximately 180degrees. Each lug 44 has a crosshole 47 which is formed through it. Thecrossholes 47 are aligned so that they have a common centerline 49. Intransmitting rotational power, the lugs 44 connect the driveshaftassembly to another portion of a driveline assembly (not depicted).

The tube seat 42 also comprises a plurality of stiffening ribs 68. Theplurality of stiffening ribs 68 are attached to the wall 46 and the base48. For example, the plurality of stiffening ribs 68 may be attached tothe inner surfaces 50, 60 of the wall 46 and the base 48.

The plurality of stiffening ribs 68 reduce the amount of radialdeformation experienced by the tube yoke 40 and, specifically, the tubeseat 42 when a torque force is applied to the driveshaft assembly. Forthe purposes of explaining the advantages of the present invention,radial deformation shall refer to a change in the shape of the tube seat42. Radial deformation, especially non-uniform radial deformation, canoccur to a tube seat when torque is applied to the driveshaft assemblyin a clockwise direction with respect to the central axis 41 and whentorque is applied in a counterclockwise direction with respect to theaxis 41.

In the embodiments depicted in FIGS. 2-16, the plurality of stiffeningribs 68 includes four ribs. However, it should be appreciated that thepresent invention can be practiced with as few as two stiffening ribsand more than four stiffening ribs. Each stiffening rib 68 comprises anouter end portion 70, a middle portion 72, an inner end portion 74, anda pair of side portions 76.

The inner surfaces 50, 60 of the wall 46 and the base 48 and theportions 70, 72, 74, 76 of the stiffening ribs 68 define an innersurface of the tube seat 42. The inner surface of the tube seat 42extends between the inner surface 60 of the base 48 and the end surface51 of the wall 46. Portions of the inner surfaces 50, 60 of the wall 46and the base 48 and the plurality of stiffening ribs 68 may vary betweenembodiments of the present invention. Thus, portions of the innersurface of the tube seat 42 can vary between embodiments of the presentinvention.

In certain embodiments, like those depicted in FIGS. 2 and 5, theplurality of stiffening ribs 68 are formed in a unitary manner with eachother. In these embodiments, each rib inner end portion 74 is attachedto an adjacent rib inner end portion 74 proximate the center portion 64of the base 48. In other embodiments, like those depicted in FIGS. 8, 11and 14, the plurality of stiffening ribs 68 are not formed as a unitarybody and are not attached to each other. In these embodiments, the innerend portion 74 of each stiffening rib is attached to the inner surface60 of the base 48 and not to the inner end portion of an adjacentstiffening rib. In these embodiments, the stiffening ribs 68 do notextend radially from the wall 46 to the central axis 41 extendingthrough the base 48, instead each stiffening rib 68 terminates adjacentan outer portion of the center portion 64 of the base 48.

Preferably, the plurality of stiffening ribs 68 are formed in a unitarymanner with the wall 46 and the base 48. For example, the plurality ofstiffening ribs 68 may be formed in a unitary manner with the innersurface 50 of the wall 46 and/or the inner surface 60 of the base 48.However, it should be appreciated that the plurality of stiffening ribs68 need not be formed in a unitary manner with either the wall 46 or thebase 48 to practice the invention.

The wall 46 surrounds the plurality of stiffening ribs 68. As shown inthe embodiments depicted in FIGS. 2 and 5, at least one pair 78 ofstiffening ribs 68 may extend from an inner edge 75 to an opposite inneredge 77 of the wall 46. However, in other embodiments, like those shownin FIGS. 8, 11 and 14, a pair of stiffening ribs 79 do not extend frominner edge 75 to inner edge 77 of the wall 46. In these embodiments, thestiffening ribs 68 terminate adjacent to and are separated by the centerportion 64 of the base 48. As best shown in FIGS. 9, 12, 15, in theseembodiments the inner surface 60 of the base 48 adjacent the centerportion 64 has a generally conical shape and may include a semisphericalshaped portion.

The stiffening rib outer end portions 70 are attached to the innersurface 50 of the wall 46. However, their position with respect to thewall 46 may vary. In certain embodiments, like those depicted in FIGS.2, 8, 11 and 14, the rib outer end portions 70 are attached to the wall46 but they do not extend the full height 55 of the wall 46. In theseembodiments, the rib outer end portions 70 may extend less than half theheight 55, approximately half of the height 55, or more than half of theheight 55 of the wall 46. However, as depicted in the embodiment shownin FIG. 5, the rib end outer portions 70 may extend approximately theentire height 55 of the wall 46. In this embodiment, the rib outer endportions 70 terminate adjacent the end surface 51 of the wall 46.

As discussed, each stiffening rib 68 is also attached to the base 48.However, each stiffening rib 68 is separated from its neighboring rib(s)by a portion 82 of the inner surface 60 of the base 48. Additionally,these portions 82 of the base 48 may assume a variety of shapes, sizesand configurations.

For example, in an embodiment best shown in FIG. 3, the portions 82 ofthe base inner surface 60 separating the plurality of stiffening ribs 68may have a tapered profile 86. In another embodiment, the plurality ofstiffening ribs 68 are positioned so as to form a unitary cross pattern.In this embodiment, the stiffening ribs 68 and their respective sideportions 76 are spaced apart from each other at an angle ofapproximately 90 degrees with respect to the central axis 41 extendingthrough the base. In this embodiment, the base portions 82 may have agenerally triangular or pie shape. Also, the base portions 82 may bedefined by the rib side portions 76 and the inner surface 50 of the wall46.

However, those skilled in the art would appreciate that the portions 82of the base 48 which separate the plurality of stiffening ribs 68 may beprovided in a number of alternative shapes or defined in other fashions.Thus, in other embodiments, the portions 82 of the inner surface 60 ofthe base 48 separating the plurality of stiffening ribs 68 may begenerally elliptical, semi-circular, rectangular, or polygonal shaped.Additionally, the base portions 82 may only be partially defined by therib side portions 76 and/or the inner surface 50 of the wall 46.

Features of the stiffening ribs 68 may also vary between embodiments ofthe present invention. For example, in the embodiment shown in FIGS.5-7, the plurality of stiffening ribs 68 may each comprise a fillet 88on each side portion 76 adjacent where the stiffening rib 68 attaches tothe inner surface 60 of the base 48. In another embodiment, which isdepicted in FIGS. 8-10, each stiffening rib 68 has a single discrete topsurface 80.

However, it should be appreciated that the present invention may bepracticed when the stiffening ribs 68 have a plurality of discretesurfaces or when the discrete surface is not the top surface 80. Forexample, in the embodiment shown in FIGS. 11-13, each stiffening rib 68has at least four discrete surfaces. In this embodiment, there exists adiscrete top surface 81, a front surface 83, and side surfaces 85, 87.Additionally, each surface 81, 83, 85, 87 has a generally rectangularshape. Those skilled in the art would appreciate that the presentinvention is not limited to discrete surfaces having only a generallyrectangular shape. For example, in a related embodiment shown in FIGS.14-16, each stiffening rib 68 has a discrete top surface 89, frontsurface 91, and two side surfaces 93, 95. However, the front and topsurfaces 89, 91 have a generally square shape. Whereas, the sidesurfaces 93, 95 have a generally triangular shape.

Of course it should be appreciated that the plurality of stiffening ribs68 need not have surfaces which are discrete in order to practice thepresent invention. As shown in the embodiments depicted in FIGS. 2 and5, the stiffening ribs 68 do not have discrete top, front, or sidesurfaces. Rather, in these embodiments, the portions 82 of the baseinner surface 60 and the plurality of stiffening ribs 68 provide aseries of alternating crests and valleys. Thus, along with the wall 46which surrounds them, the base inner surface 60 and the plurality ofstiffening ribs 68 define an undulating cavity 90.

As depicted in the embodiments illustrated in FIGS. 2, 5, 8, 11 and 14,the plurality of stiffening ribs 68 are attached to the inner surface 50of the wall 46 between the inner surface 60 of the base 48 and the endsurface 51 of the wall 46. In these embodiments, a portion of thestiffening ribs 68 between the inner surface 60 of the base 48 and theend surface 51 of the wall 46 gradually decreases the thickness. Forexample, the thickness of each stiffening rib 68 may gradually decreasesfrom its inner end portion 74 to where its outer end portion 70 isattached to the inner surface 50 of the wall 46. In another embodiment,the thickness of each stiffening rib 68 may gradually decrease from itsside portions 76 to where its outer end portion 70 is attached to theinner surface 50 of the wall 46. In yet another embodiment, thethickness of each stiffening rib 68 may gradually decrease from itsmiddle portion 72 to where its outer end portion 70 is attached to theinner surface 50 of the wall 46. Additionally, as shown in FIGS. 2 and 5the thickness of the unitarily formed stiffening ribs 68 may graduallydecreases from adjacent the center portion 64 of the base 48 to theinner surface 50 of the wall 46, specifically, to where each stiffeningrib's outer end portion 70 is attached to the inner surface 50 of thewall 46.

In an embodiment, each stiffening rib 68 is oriented at an acute anglewith respect to the common centerline 49 of the crossholes 47. Inanother embodiment, each stiffening rib 68 is oriented at same angle asan adjacent stiffening rib 68 with respect to the common centerline 49of the crossholes 47. More specifically, when included as a component ofthe driveshaft assembly and under certain torque forces, the tube yoke40 may undergo a certain amount of non-uniform radial deformation. Theareas of greatest non-uniform radial tube seat deformation may beadjacent a portion of the tube seat 42 which is oriented at an angle ofapproximately 45 degrees with respect to the common centerline 49 of thecrossholes 47. Thus, in an embodiment, each stiffening rib 68 isoriented at an angle of approximately 45 degrees with respect to thecommon centerline 49 of the crossholes 47.

It should however be appreciated that the orientation of the stiffeningribs 68 with respect to the lugs 44, specifically the common centerline49 of the crossholes 47, may vary without departing from the scope ofthe present invention. Additionally, the orientation of the stiffeningribs 68 with respect to the wall 46 and the base 48 may vary withoutdeparting from the scope of the present invention.

FIGS. 17-20 depict additional embodiments of a tube yoke 100, 120 for adriveshaft assembly.

When utilizing the tube yokes 100, 120 it is preferable that they areattached to a driveshaft tube (not depicted) to form the driveshaftassembly.

As depicted in FIGS. 17 and 18, in an embodiment the tube yoke 100comprises a tube seat 102 and the pair of outwardly projecting lugs 44.The lugs 44 are formed in a unitary manner with the tube seat 102.

The tube seat 102 comprises the wall 46 and a base 104. The wall 46 andthe base 104 are formed in a unitary manner. Additionally, the wall 46and the base 104 are concentric about an axis 111.

The base 104 has an inner surface 106 and outer surface 62. The innersurface 106 of the base 104 and the inner surface 50 of the wall 46define an inner surface of the tube seat 102. The inner surface of thetube seat 102 extends between the inner surface 106 of the base 104 andthe end surface 51 of the wall 46.

The base 104 also has a center portion 108 which extends from the innersurface 106 to the outer surface 62. The inner surface 106 has edgeportions 110 and a rounded middle portion 112. The middle portion 112and the edge portions 110 are coaxial and are formed in a unitarymanner. In an embodiment, the middle portion 112 is adjacent the centerportion 108 and the edge portions 108 completely surround the middleportion 112 separating it from the inner surface 106 of the wall 46. Inanother embodiment, the middle portion 112 has a generally conicalshape. In this embodiment, the middle portion 112 may also include asemispherical shaped portion.

As best shown in FIG. 18, the edge portions 110 taper to the middleportion 112 and the wall 46. Thus, the thickness of the base 104gradually decreases from the edge portions 110 to the middle portion 112and from the edge portions 110 to the wall 46 to provide the innersurface of the tube seat 102 with a generally conical shape. In thisembodiment, the inner surface of the tube seat 102 may be substantiallyuniform about the axis 111. Thus, its conical shape may also besubstantially uniform about the axis 111.

As shown in the embodiment depicted in FIGS. 19 and 20, the tube yoke120 comprises a tube seat 122 and the pair of outwardly projecting lugs44. The lugs 44 are formed in a unitary manner with the tube seat 122.

The tube seat 122 comprises a wall 124 and a base 126. The wall 124 andthe base 126 are formed in a unitary manner. Additionally, the wall 124and the base 126 are concentric about an axis 131.

The wall 124 has an inner surface 128, end surface 51, and outer surface52. The base 126 has an inner surface 130 and outer surface 62. Theinner surface 130 of the base 104 and the inner surface 128 of the wall124 define an inner surface of the tube seat 122. The inner surface ofthe tube seat 122 extends between the inner surface 130 of the base 126and the end surface 51 of the wall 124.

As best seen in FIG. 20, the inner surfaces 128, 130 of the wall 124 andthe base 126 provide the inner surface of the tube seat 122 with agenerally conical shape. The inner surface of the tube seat 122 may besubstantially uniform about the axis 131. Thus, its conical shape mayalso be substantially uniform about the axis 131.

In this embodiment, the inner surface 128 of the wall 124 tapers from afirst end 134 to a second end portion 136. The second end portion 136 isunitary with the inner surface 130 of the base 126. The inner surface130 of the base 126 tapers till it reaches a center portion 132 of thebase 126. The center portion 132 extends from the inner surface 130 tothe outer surface 62 of the base 126. The inner surface 130 of the base126 adjacent the center portion 132 is rounded such that it may includea generally semispherical shaped portion. Thus, as illustrated anddescribed, the thickness of the tube seat 122 gradually decreasesbetween the inner surface 130 of the base 126 and the end surface 51 ofthe wall 124.

It should be appreciated that the tube yokes 40, 100, 120 can be made ofany suitable material but are preferably metallic. It is also preferablethat the tube yokes 40, 100, 120 are formed as a unitary body.

Referring back to FIGS. 2-16, the tube yoke 40 having a plurality ofstiffening ribs 68 provides a significant reduction in non-uniformradial tube seat deformation experienced by the tube yoke 40 whencompared with known tube yoke designs. In fact, in certain embodiments,the non-uniform radial deformation of a tube seat can be reduced tobelow 0.10 mm. For example, non-uniform radial tube seat deformation of0.143 mm can be reduced to 0.089 mm for a tube seat for driveshaftassembly with a 4″ diameter driveshaft tube. This represents a 38%reduction in non-uniform radial tube seat deformation. The presentinvention can reduce non-uniform radial deformation of a tube seat for adriveshaft assembly with a 5″ diameter driveshaft tube as well. For thistube seat, the non-uniform radial deformation can be reduced from 0.174mm to 0.102 mm which represents a 41% reduction in non-uniform radialtube seat deformation. Of course, it should be appreciated that thepresent invention can be utilized to reduce the non-uniform radialdeformation of tube seats intended for use in both larger and smallerdriveshaft assemblies.

It should be noted that in the above-described examples that the torqueforce was applied in both a clockwise and a counterclockwise direction.However, the present invention is not limited to a specific direction ofapplied torque as the present invention can reduce the non-uniformradial deformation of a driveshaft assembly tube yoke regardless ofwhich direction torque is applied to the driveshaft. Thus, the presentinvention also includes a method of reducing the radial deformation ofthe tube yoke of a driveshaft assembly.

The method of reducing the radial deformation of a driveshaft assemblycomprises providing a driveshaft assembly. The driveshaft assemblyincludes a driveshaft tube and a tube yoke 40, 100, 120. The driveshafttube is attached to the tube yoke 40, 100, 120. The tube yoke 40, 100,120 comprises a tube seat 42, 102, 122 having a base 48, 104, 126 and awall 46, 124.

The method also includes reducing the amount of radial deformation ofthe tube seat 42, 102, 122. In an embodiment, the amount of radialdeformation of the tube seat 42 is reduced by providing a plurality ofstiffening ribs 68 attached to the tube seat 42. In another embodiment,the amount of radial deformation of the tube seat 42, 102, 122 may bereduced by forming an inner surface of the tube seat 42, 102, 122 with agenerally conical shaped portion. The method may further compriseapplying a torque to the driveshaft assembly. The magnitude of thetorque may vary.

In accordance with the provisions of the patent statutes, this inventionhas been explained and illustrated in its preferred embodiments.However, it must be understood that this invention may be practicedotherwise than as specifically explained and illustrated withoutdeparting from its spirit or scope.

What we claim is:
 1. A tube yoke for a driveshaft assembly, comprising:a tube seat comprising a base, a wall, and two pairs of stiffening ribs,wherein the two pairs of ribs are formed as one unitary body thatconnect at said base, wherein the stiffening ribs extend between aninner surface of the base and an end surface of the wall and eachstiffening rib comprises an outer end portion which is attached to awall middle portion and a pair of side portions; and a pair of lugsoutwardly projecting from the tube seat, wherein each lug has acrosshole and the crossholes are aligned so as to have a commoncenterline; wherein each stiffening rib is oriented at an acute anglewith respect to the common centerline of the crossholes, each stiffeningrib extends to the end surface of the wall, wherein in each pair one ofthe stiffening ribs of the pair is oriented opposite the otherstiffening rib of the pair, wherein said oppositely oriented stiffeningribs are unitarily connected along said inner surface of said base witha fillet but do not extend across an opening of said wall surroundingeach stiffening rib.
 2. The tube yoke defined in claim 1, wherein thebase gradually decreases in thickness toward a central axis extendingthrough the base.
 3. The tube yoke defined in claim 1, wherein the basegradually decreases in thickness from the wall to a center portion ofthe base.
 4. The tube yoke defined in claim 1, wherein the plurality ofstiffening ribs are attached to an inner surface of the wall such thatthe wall surrounds the plurality of stiffening ribs.
 5. The tube yokedefined in claim 1, wherein the acute angle is equal to approximately 45degrees.
 6. The tube yoke defined in claim 1, wherein the plurality ofstiffening ribs are attached to the base and the wall and reduce theamount of radial deformation experienced by the tube seat when a torqueforce is applied.
 7. The tube yoke defined in claim 1, wherein theplurality of stiffening ribs are formed in a unitary manner such thatthe plurality of stiffening ribs are configured in a unitary crosspattern and each stiffening rib is spaced apart from an adjacentstiffening rib at an angle of 90 degrees with respect to a central axisextending through the base.
 8. A tube yoke for a driveshaft assembly,comprising: a tube seat comprising a base, a wall, and two pairs ofstiffening ribs, wherein each stiffening rib comprises an outer endportion which is attached to a wall middle portion and a pair of sideportions and a front surface; and a pair of lugs outwardly projectingfrom the tube seat, wherein each lug has a crosshole and the crossholesare aligned so as to have a common centerline; wherein each stiffeningrib is oriented at an acute angle with respect to the common centerlineof the crossholes, each stiffening rib terminates before it reaches theend surface of the wall in a discrete rectangular top surface, whereineach stiffening rib terminates before it reaches a base center portion,wherein at least a portion of said pair of side portions and said frontsurface of each have a rectangular shape, wherein in each pair one ofthe stiffening ribs of the pair is oriented opposite the otherstiffening rib of the pair, wherein said oppositely oriented stiffeningribs are unitarily connected along said inner surface of said base butdo not extend across an opening of said wall surrounding each stiffeningrib.
 9. The tube yoke defined in claim 8, wherein the base graduallydecreases in thickness toward a central axis extending through the base.10. The tube yoke defined in claim 8, wherein the base graduallydecreases in thickness from the wall to a center portion of the base.11. The tube yoke defined in claim 8, wherein the plurality ofstiffening ribs are attached to an inner surface of the wall such thatthe wall surrounds the plurality of stiffening ribs.
 12. The tube yokedefined in claim 8, wherein the acute angle is equal to approximately 45degrees.
 13. The tube yoke defined in claim 8, wherein the plurality ofstiffening ribs are attached to the base and the wall and reduce theamount of radial deformation experienced by the tube seat when a torqueforce is applied.
 14. A tube yoke for a driveshaft assembly, comprising:a tube seat comprising a base, a wall, and two pairs of stiffening ribs,wherein each stiffening rib comprises a portion attached to the wall anda pair of side portions; and a pair of lugs outwardly projecting fromthe tube seat, wherein each lug has a crosshole and the crossholes arealigned so as to have a common centerline; wherein each stiffening ribis oriented at an acute angle with respect to the common centerline ofthe crossholes, each stiffening rib terminates before it reaches an endsurface of the wall in a discrete polygon top surface, wherein eachstiffening rib terminates in a discrete polygon front surface before itreaches said base so that the ribs do not form a unitary body with oneanother, wherein at least a portion of said pair of side portions have adiscrete polygon shape, wherein in each pair one of the stiffening ribsof the pair is oriented opposite the other stiffening rib of the pair,wherein said oppositely oriented stiffening ribs are unitarily connectedalong said inner surface of said base but do not extend across anopening of said wall surrounding each stiffening rib.
 15. The tube yokedefined in claim 15, wherein the base gradually decreases in thicknesstoward a central axis extending through the base.
 16. The tube yokedefined in claim 15, wherein the base gradually decreases in thicknessfrom the wall to a center portion of the base.
 17. The tube yoke definedin claim 15, wherein the plurality of stiffening ribs are attached to aninner surface of the wall such that the wall surrounds the plurality ofstiffening ribs.
 18. The tube yoke defined in claim 15, wherein theacute angle is equal to approximately 45 degrees.
 19. The tube yokedefined in claim 15, wherein the plurality of stiffening ribs areattached to the base and the wall and reduce the amount of radialdeformation experienced by the tube seat when a torque force is applied.